Dry-type transformer waste heat recycling system and method

Abstract

The application discloses a dry-type transformer waste heat recycling system and method, wherein the system comprises: a dry-type transformer body contained in a shell; an air induction system arranged at the top of the shell; a plurality of series-connected phase change heat storage containers, each of which is provided with phase change heat storage material; the air induction system is connected with the first phase change heat storage container through a pipeline; a phase change shell is arranged on the shell and is connected with the plurality of phase change heat storage containers in parallel, the phase change shell is internally provided with phase change material, and the top of the phase change shell is provided with a temperature sensing probe and a heat exchanger. The application can ensure the relative stability of the internal temperature of the shell under the condition of environmental temperature change without changing the use condition of the dry-type transformer and without contacting the dry-type transformer body, can ensure the stability and controllability of waste heat output under the condition of environmental temperature change through the gradient recycling of the waste heat of the dry-type transformer by the multi-stage phase change heat storage structure, and can reduce the land occupation size of the system.

Description

Technical Field

[0001] This invention belongs to the field of transformer technology, specifically relating to a waste heat recovery and utilization system and method for dry-type transformers. Background Technology

[0002] Compared to oil-immersed transformers, dry-type transformers significantly reduce the risks of combustion, explosion, and pollution, thus enjoying widespread application both domestically and internationally. The core and windings of a dry-type transformer are sealed in insulating epoxy resin, dissipating heat through air convection and conduction, resulting in relatively slow heat dissipation during power conversion. Cooling methods for dry-type transformers are divided into natural convection cooling and forced convection cooling. Under design conditions, natural convection cooling allows the transformer to operate continuously at its rated capacity for extended periods, but the temperature of the internal core and windings rises significantly relative to the ambient temperature. Forced convection cooling lowers the internal temperature relative to the ambient temperature, increasing the maximum output capacity by up to 50%. Therefore, most dry-type transformers employ forced air cooling. Specifically, a fan is installed below the windings. When the winding temperature exceeds a set limit, the fan activates, rapidly increasing airflow speed and significantly improving the convective heat transfer coefficient between the air and the winding surface, thereby greatly enhancing the heat dissipation rate and cooling speed of the windings.

[0003] Currently, dry-type transformers only dissipate heat without recycling it, causing thermal pollution to the environment. Meanwhile, transformer waste heat has significant potential for utilization. Waste heat recovery from transformers can not only generate substantial energy-saving benefits but also reduce thermal pollution, resulting in significant energy conservation and emission reduction effects.

[0004] However, the waste heat parameters of transformers are complex and variable. The internal temperature and flow rate of equipment used in different regions may vary at different times and in different seasons, leading to a high degree of complexity and significant variations in waste heat recovery. Transformers have temperature limitations, and their heat dissipation is crucial to equipment safety and lifespan. Therefore, while utilizing waste heat, it is essential to ensure effective heat dissipation. Consequently, there is currently no stable solution for recovering and utilizing transformer waste heat. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a dry-type transformer waste heat recovery and utilization system and method, so as to utilize the complex and variable waste heat of the dry-type transformer to provide a stable heat source for the surrounding area, thereby achieving the dual effects of waste heat recovery and equipment safety.

[0006] To solve the above-mentioned technical problems, the present invention provides a dry-type transformer waste heat recovery and utilization system, comprising:

[0007] The dry-type transformer body is housed within an outer casing;

[0008] An exhaust system is installed at the top of the housing;

[0009] The system comprises a series of multi-stage phase change heat storage containers, each containing phase change heat storage material; the exhaust system is connected to the first-stage phase change heat storage container via a pipeline.

[0010] A phase change housing is disposed on the outer shell and connected in parallel with a multi-stage phase change heat storage container. The interior of the phase change housing is a phase change material, and a temperature sensing probe and a heat exchanger are provided on the top of the phase change housing.

[0011] The exhaust system is used to introduce hot air, which has been heated by absorbing the waste heat of the dry-type transformer, into a series of multi-stage phase change heat storage containers, and then discharge it into the atmosphere after cooling. The multi-stage phase change heat storage containers are used to draw fluid to the user side as needed.

[0012] Furthermore, in a series-connected multi-stage phase change heat storage container, the phase change heat storage material in the last stage phase change heat storage container is a small sphere covered with metal, and the outside is fluid.

[0013] Furthermore, hot air flows sequentially through the multi-stage phase change heat storage container, and the phase change temperature of the phase change heat storage material in different phase change heat storage containers in the direction of hot air flow decreases sequentially.

[0014] Furthermore, the external heat exchange surface of the phase change shell heat exchanger is in contact with the phase change material, and the inside of the heat exchanger pipe is a heat exchange fluid.

[0015] Furthermore, the phase change temperature of the phase change material inside the phase change shell has two modes: it is equal to or less than the lowest phase change temperature among the phase change materials in the multi-stage phase change heat storage container; or it is less than the lowest phase change temperature among the phase change materials in all the previous non-final stage phase change heat storage containers and higher than the phase change temperature of the phase change material in the final stage phase change heat storage container.

[0016] Furthermore, when the dry-type transformer waste heat recovery system operates in a low-temperature environment mode, the induced draft system draws hot air into the first-stage phase change heat storage container, where the working fluid absorbs heat. The cooled air from the first-stage phase change heat storage container passes through subsequent phase change heat storage containers until it reaches the final-stage phase change heat storage container, and is then discharged into the atmosphere after cooling. During periods when heat is needed, fluid is drawn from either the first-stage or final-stage phase change heat storage container to the user side, based on the required temperature.

[0017] Furthermore, when the waste heat recovery system of the dry-type transformer operates in high-temperature mode, the working fluid inside the phase change shell becomes liquid. When the temperature parameter measured by the temperature sensor is higher than the set value, the circulation pump is activated. The heat exchange fluid flowing in the heat exchanger absorbs the heat and rises in temperature before entering the final-stage phase change heat storage container. Heat is stored by circulating and heating the phase change working fluid and the flowing working fluid to reduce the operating temperature of the dry-type transformer body. The waste heat generated during the operation of the dry-type transformer is drawn out by the exhaust system and first enters the first-stage phase change heat storage container, then passes through the subsequent stages of phase change heat storage containers until the final-stage phase change heat storage container, and is discharged into the atmosphere after cooling. During the period when heat is needed, fluid is drawn from the first-stage or final-stage phase change heat storage container to the user side according to the temperature requirements of the heat use.

[0018] Furthermore, when the dry-type transformer waste heat recovery system operates in the ambient temperature change mode, if the ambient temperature is low, it operates according to the low-temperature environment mode; after the ambient temperature rises, a gradient with a high upper temperature and a low lower temperature is formed inside the phase change shell. When the temperature parameter measured by the temperature sensor is higher than the set value, the circulation pump is started, and it operates according to the high-temperature mode; after the working fluid inside the phase change shell cools down, it forms vertical convection, thereby reducing the internal temperature of the phase change shell; when the temperature measured by the temperature sensor drops to the limit value, the circulation pump is turned off, the temperature reduction of the phase change shell decreases, and the working fluid inside the phase change shell gradually becomes solid.

[0019] Furthermore, when the dry-type transformer waste heat recovery system operates in variable connection mode, the phase change temperature of the working fluid in the phase change shell is lower than that in the secondary phase change heat storage container but higher than that in the final phase change heat storage container. When the temperature measured by the temperature sensor is higher than the phase change temperature in the final phase change heat storage container and reaches the first temperature limit, the circulation pump is started, the first valve is closed, and the second valve is opened. When the temperature measured by the temperature sensor is higher than the phase change temperature in the secondary phase change heat storage container and reaches the second temperature limit, the second valve is opened, where the second temperature limit is greater than the first temperature limit. When the temperature measured by the temperature sensor begins to decrease, the first valve is closed first. If the temperature measured by the temperature sensor continues to decrease to the second temperature limit, the second valve is closed and the first valve is opened. When the temperature measured by the temperature sensor continues to decrease to the third temperature limit, the circulation pump and the first valve are closed, where the third temperature limit is less than the first temperature limit.

[0020] The present invention also provides a method for recovering and utilizing waste heat from a dry-type transformer, which is implemented based on the aforementioned waste heat recovery and utilization system for dry-type transformers.

[0021] The implementation of this invention has the following beneficial effects: Based on the concept of stable waste heat utilization, this invention, without changing the operating conditions of the dry-type transformer or contacting the transformer body, recovers the waste heat of the complex and variable dry-type transformer in stages through multi-stage phase change heat storage, providing a stable heat source for the surrounding area, effectively maintaining the stability of waste heat utilization parameters, improving the quality of waste heat utilization, and reducing the system footprint. It is more suitable for common situations where domestic hot water and other applications are concentrated in a certain period of time, which is beneficial for waste heat recovery and utilization under transformer load change conditions, resulting in significant energy saving and emission reduction effects. At the same time, by using phase change materials inside the transformer shell, the heat dissipation effect in high-temperature environments is improved, the operating temperature of the dry-type transformer body is reduced, the heat dissipation in low-temperature environments is reduced, and the temperature difference between the inside and outside of the equipment body is reduced, ensuring the relative stability of the internal temperature of the shell under ambient temperature changes, thereby ensuring the safety of the dry-type transformer body, extending the service life of the equipment, and achieving effective adaptation to changes in the external environment, achieving the dual effects of waste heat recovery and equipment safety. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the principle of a dry-type transformer waste heat recovery and utilization system according to Embodiment 1 of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the principle of waste heat utilization in the converter circuit of a dry-type transformer in an embodiment of the present invention. Detailed Implementation

[0025] The following descriptions of the embodiments are with reference to the accompanying drawings, illustrating specific embodiments in which the present invention can be implemented. The directional and positional terms mentioned in the embodiments of the present invention, such as "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "top," "bottom," and "side," are merely for reference to the directions or positions in the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding the present invention, and not for limiting the scope of protection of the present invention.

[0026] Please refer to Figure 1 As shown, Embodiment 1 of the present invention provides a dry-type transformer waste heat recovery and utilization system, comprising:

[0027] The dry-type transformer body is housed within an outer casing;

[0028] An exhaust system is installed at the top of the housing;

[0029] The system comprises a series of multi-stage phase change heat storage containers, each containing phase change heat storage material; the exhaust system is connected to the first-stage phase change heat storage container via a pipeline.

[0030] A phase change housing is disposed on the outer shell and connected in parallel with a multi-stage phase change heat storage container. The interior of the phase change housing is a phase change material, and a temperature sensing probe and a heat exchanger are provided on the top of the phase change housing.

[0031] The exhaust system is used to introduce hot air, which has been heated by absorbing the waste heat of the dry-type transformer, into a series of multi-stage phase change heat storage containers, and then discharge it into the atmosphere after cooling. The multi-stage phase change heat storage containers are used to draw fluid to the user side as needed.

[0032] Specifically, this embodiment does not limit the number of multi-stage phase change thermal storage containers connected in series. As an example, it may include a first-stage phase change thermal storage container 2 and a final-stage phase change thermal storage container 3 (see [link]). Figure 1 ), or includes a first-stage phase change thermal storage vessel 2, a second-stage phase change thermal storage vessel 2', and a final-stage phase change thermal storage vessel 3 (see Figure 2 The phase change materials inside the multi-stage phase change heat storage containers have different phase change temperatures. In the final stage phase change heat storage container 3, the phase change material is a small sphere covered with metal, and the exterior is filled with a fluid such as water or antifreeze. The induced draft system is specifically a blower 12. Air entering the phase change shell 4 through the air inlet 14 absorbs the waste heat from the dry-type transformer and becomes heated. The blower 12 then introduces the hot air into the first-stage phase change heat storage container 2. Subsequently, the hot air flows sequentially through the multi-stage phase change heat storage containers, and the phase change temperature of the phase change material in the different phase change heat storage containers along the direction of air flow decreases sequentially.

[0033] The external heat exchange surface of the heat exchanger 11 in the phase change shell 4 is in contact with the phase change material, and the inside of the pipes of the heat exchanger 11 is filled with heat exchange fluid. It should be noted that the phase change temperature of the phase change material inside the phase change shell 4 is equal to or less than the lowest value among the phase change temperatures of the various phase change heat storage materials in the multi-stage phase change heat storage container.

[0034] This invention realizes the utilization of external waste heat of dry-type transformers by adding a multi-stage series-parallel phase change heat storage structure, thereby achieving stable management of the external ambient temperature of dry-type transformers and ensuring the stability and controllability of waste heat output under the conditions of winter and summer and day and night ambient temperature changes, thus improving the safety and operational stability of dry-type transformers.

[0035] The following combination Figure 2 The working mode, working principle and process of a dry-type transformer waste heat recovery and utilization system in this embodiment are described respectively.

[0036] (1) Low-temperature environment mode

[0037] Because the ambient temperature is low, the working fluid inside the phase change reactor (PCR) housing 4 becomes solid, resulting in low thermal conductivity. During operation, the dry-type transformer generates residual heat, but dissipates little heat to the outside, leading to a high internal temperature. The induced draft fan 12 draws out relatively hot air, which first enters the first-stage PCR heat storage container 2. The working fluid in the first-stage PCR heat storage container 2 absorbs heat, exhibiting a large latent heat of phase change, allowing its internal temperature to remain stable for an extended period. The cooled air from the first-stage PCR heat storage container 2 then passes through subsequent stages of PCR heat storage containers until reaching the final stage PCR heat storage container 3, where it is cooled further and discharged into the atmosphere. During periods of heat demand, fluid is drawn from either the first-stage PCR heat storage container 2 or the final stage PCR heat storage container 3 and delivered to the user side, based on the required temperature.

[0038] (2) High Temperature Pattern

[0039] When the ambient temperature is high, the air temperature inside the phase change housing 4 and outer shell 5, and outside the dry-type transformer body 1, is also higher than the ambient temperature. Under these conditions, the dry-type transformer operates at a high temperature. The working fluid inside the phase change housing 4 becomes liquid. If the temperature parameter measured by the temperature sensor 31 built into the phase change housing 4 is higher than the set value, the circulation pump 13 will be activated. The internal fluid (water or antifreeze) flows in the heat exchanger 11 built into the phase change housing 4, absorbing heat and rising in temperature before entering the final-stage phase change heat storage container 3. Heat is stored by circulating and heating the phase change working fluid and the flowing working fluid, while the temperature of the phase change housing 4 decreases, thereby reducing the operating temperature of the dry-type transformer body 1. The waste heat generated during the operation of the dry-type transformer is drawn out by the induced draft fan 12, and also enters the first-stage phase change heat storage container 2. This heat then passes through subsequent phase change heat storage containers until it reaches the final-stage phase change heat storage container 3, where it is cooled and then discharged into the atmosphere. During periods when heat is needed, fluid is drawn from either the first-stage phase change heat storage container 2 or the final-stage phase change heat storage container 3 to the user side, based on the required temperature. The presence of the phase change shell and its heat exchange circulation significantly reduces the temperature of the air inside the phase change shell 4 and the outer shell 5, ensuring the safe operation of the dry-type transformer in high-temperature environments.

[0040] (3) Ambient temperature change pattern

[0041] When the air temperature is low, the operation is firstly carried out according to the aforementioned mode (1); as the temperature rises, the temperature of the air inside the phase change shell 4 rises, and a gradient of high temperature in the upper part and low temperature in the lower part is formed due to density. The temperature of the upper part of the phase change shell 4 continues to rise, the internal solid material gradually liquefies, and the temperature value measured by the temperature sensing probe 31 also gradually increases. When the value reaches the set value, the circulating pump 13 is started to operate according to the aforementioned mode (2).

[0042] (4) Variable connection mode

[0043] The phase change temperature of the working medium in the phase change shell 4 is lower than the minimum value among the phase change temperatures of each phase change heat storage material in all preceding non-final-stage phase change heat storage containers and higher than the phase change temperature of the phase change heat storage material in the final-stage phase change heat storage container. Regulation is performed through valves based on the temperatures among the three, so as to ensure stable heat storage and stable temperature of the phase change shell 4. When the temperature measured by the temperature sensing probe 31 is higher than the phase change temperature in the final-stage phase change heat storage container 3 and reaches the first temperature limit T1, the circulating pump 13 is started, the valve 51 is closed, and the valve 52 is opened; as the heat storage amount increases and the ambient temperature rises, the temperature measured by the temperature sensing probe 31 may continue to increase. If the measured temperature is higher than the phase change temperature in the penultimate-stage phase change heat storage container 2' and reaches the second temperature limit T2 (T2>T1), the valve 52 is opened (at this time, the valve 51 is in an open state). When the temperature measured by the temperature sensing probe 31 starts to decrease, the valve 51 is closed first; if the temperature measured by the temperature sensing probe 31 continues to decrease to the second temperature limit T2, the valve 52 is closed and the valve 51 is opened; and when the temperature measured by the temperature sensing probe 31 continues to decrease to the third temperature limit T3 (T3<T1), the circulating pump 13 is stopped and the valve 51 is closed.

[0044] Embodiment 2 of the present invention further provides a waste heat recovery and utilization method for dry-type transformers, which is implemented based on the aforementioned waste heat recovery and utilization system for dry-type transformers in Embodiment 1 of the present invention. For the working principle and process of this embodiment, please refer to the description of the aforementioned Embodiment 1, which will not be repeated here.

[0045] As can be seen from the above description, compared with the prior art, the beneficial effects of the present invention are as follows: Based on the idea of ​​stable utilization of waste heat, the present invention utilizes the waste heat of complex and variable dry-type transformers through multi-stage phase change heat storage to provide a stable heat source for the surrounding area. It has a large heat storage capacity, small footprint, and stable heat output parameters, making it more suitable for common situations such as domestic hot water use concentrated at certain times. It is beneficial for the recovery and utilization of waste heat under transformer load change operation, enabling year-round heating and waste heat utilization, resulting in significant energy saving and emission reduction effects. At the same time, by using phase change materials in the transformer shell, the heat dissipation effect in high-temperature environments is improved, reducing the operating temperature of the dry-type transformer equipment body, reducing heat dissipation in low-temperature environments, reducing the temperature difference between the inside and outside of the equipment body, extending the service life of the equipment, and achieving effective adaptation to changes in the external environment, thus achieving the dual effects of waste heat recovery and equipment safety.

[0046] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A waste heat recovery and utilization system for dry-type transformers, characterized in that, include: The dry-type transformer body is housed within an outer casing; An exhaust system is installed at the top of the housing; The system comprises a series of multi-stage phase change heat storage containers, each containing phase change heat storage material; the exhaust system is connected to the first-stage phase change heat storage container via a pipeline. A phase change housing is disposed on the outer shell and connected in parallel with a multi-stage phase change heat storage container. The interior of the phase change housing is a phase change material, and a temperature sensing probe and a heat exchanger are provided on the top of the phase change housing. The air intake system is used to introduce hot air, which has been heated by absorbing the waste heat of the dry-type transformer, into the series-connected multi-stage phase change heat storage containers and then discharge it into the atmosphere after cooling. The multi-stage phase change heat storage containers are used to draw fluid to the user side as needed. The hot air flows sequentially in the multi-stage phase change heat storage containers, and the phase change temperature of the phase change heat storage material in different phase change heat storage containers in the direction of hot air flow decreases sequentially. The phase change temperature of the phase change material inside the phase change shell has two modes: it is equal to or less than the lowest phase change temperature among all phase change materials in the multi-stage phase change heat storage container; or it is less than the lowest phase change temperature among all phase change materials in all non-final stage phase change heat storage containers and higher than the phase change temperature of the phase change material in the final stage phase change heat storage container.

2. The waste heat recovery system for dry-type transformers according to claim 1, characterized in that, In a series of multi-stage phase change thermal storage containers, the phase change thermal storage material in the last stage phase change thermal storage container is a small sphere covered with metal, and the outside is fluid.

3. The dry-type transformer waste heat recovery and utilization system according to claim 1, characterized in that, The external heat exchange surface of the phase change shell heat exchanger is in contact with the phase change material, and the inside of the heat exchanger pipe is a heat exchange fluid.

4. The dry-type transformer waste heat recovery and utilization system according to claim 1, characterized in that, When the dry-type transformer waste heat recovery system operates in a low-temperature environment mode, the induced draft system draws hot air into the first-stage phase change heat storage container, where the working fluid absorbs heat. The cooled air from the first-stage phase change heat storage container passes through subsequent phase change heat storage containers until it reaches the final-stage phase change heat storage container, where it is cooled and then discharged into the atmosphere. During periods when heat is needed, fluid is drawn from either the first-stage or final-stage phase change heat storage container to the user side, based on the required temperature.

5. The waste heat recovery system for dry-type transformers according to claim 4, characterized in that, When the waste heat recovery system of the dry-type transformer operates in high-temperature mode, the working fluid inside the phase change shell becomes liquid. When the temperature parameter measured by the temperature sensor is higher than the set value, the circulation pump is activated. The heat exchange fluid flowing in the heat exchanger absorbs the heat and rises in temperature before entering the final-stage phase change heat storage container. Heat is stored by circulating and heating the phase change working fluid and the flowing working fluid to reduce the operating temperature of the dry-type transformer body. The waste heat generated during the operation of the dry-type transformer is drawn out by the exhaust system and first enters the first-stage phase change heat storage container, then passes through the subsequent phase change heat storage containers in sequence until the final-stage phase change heat storage container, and is discharged into the atmosphere after cooling. During the period when heat is needed, fluid is drawn from the first-stage or final-stage phase change heat storage container to the user side according to the temperature requirements of the heat use.

6. The waste heat recovery system for dry-type transformers according to claim 5, characterized in that, When the dry-type transformer waste heat recovery system operates in the ambient temperature change mode, if the air temperature is low, it operates according to the low-temperature environment mode; after the air temperature rises, a gradient of high temperature at the top and low temperature at the bottom is formed inside the phase change shell. When the temperature parameter measured by the temperature sensor is higher than the set value, the circulation pump is started and it operates according to the high-temperature mode; after the working fluid inside the phase change shell cools down, it forms vertical convection, which further reduces the internal temperature of the phase change shell; when the temperature measured by the temperature sensor drops to the limit value, the circulation pump is turned off, the temperature drop of the phase change shell decreases, and the working fluid inside the phase change shell gradually becomes solid.

7. The dry-type transformer waste heat recovery and utilization system according to claim 6, characterized in that, When the dry-type transformer waste heat recovery system operates in variable connection mode, the phase change temperature of the working fluid in the phase change shell is lower than that in the secondary phase change heat storage container but higher than that in the final phase change heat storage container. When the temperature measured by the temperature sensor is higher than the phase change temperature in the final phase change heat storage container and reaches the first temperature limit, the circulation pump is started, the first valve is closed, and the second valve is opened. When the temperature measured by the temperature sensor is higher than the phase change temperature in the secondary phase change heat storage container and reaches the second temperature limit, the first valve is opened, where the second temperature limit is greater than the first temperature limit. When the temperature measured by the temperature sensor begins to decrease, the first valve is closed first. If the temperature measured by the temperature sensor continues to decrease to the second temperature limit, the second valve is closed and the first valve is opened. When the temperature measured by the temperature sensor continues to decrease to the third temperature limit, the circulation pump and the first valve are closed, where the third temperature limit is less than the first temperature limit.

8. A method for recovering and utilizing waste heat from a dry-type transformer, characterized in that, Based on the dry-type transformer waste heat recovery and utilization system as described in any one of claims 1-7.

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